For many people, smartphones have replaced cameras as the main way to capture personal pictures and video.

The quality of the devices has greatly improved.

Even some Hollywood filmmakers have decided to stop using big, costly equipment and instead shoot movies on smartphones. One of the latest to do this is director and producer Steven Soderbergh.

Soderbergh has made both independent and big-budget films. He won an Academy Award for Best Director of the movie “Traffic” in 2001. He was also nominated that year for Best Director for “Erin Brockovich.” His earliest full length movie, Sex, Lies and Videotape, came out in 1989. Ocean’s Eleven came about four years later. Among other Soderbergh films are 2012’s Magic Mike and “Logan Lucky” released last year.

Soderbergh has also worked on several television series.

This image released by Bleecker Street showsPolly McKie, left, and Claire Foy in a scene from “Unsane.” (Bleecker Street via AP)

He describes his latest directorial effort, “Unsane,” as a psychological thriller. The film was recently released in the U.S. and several other countries. The whole film was shot on an iPhone 7 Plus.

Actress Claire Foy plays a woman who moves to a new city to escape a man who has been stalking her. After experiencing mental health difficulties, she agrees to go to a hospital.

The woman quickly decides she should not be in the mental hospital and tries to leave. But she is not permitted to go. She protests her detention. Her mother also works to get her out.

While trapped there, the woman fears her stalker now works at the hospital. It is not clear to the moviegoers if the man is really there, or if the character just imagines that.

In several interviews, the director praised his results of iPhone filming.

“I’m very happy the way the movie looks,” Soderbergh told a news conference for the film’s premiere at the Berlin International Film Festival in Germany. He said he knows some people will want to see the movie just because it was shot on an iPhone. But, he says, moviegoers will not notice anything unusual.

“Anybody going to see this movie who has no idea of the backstory to the production will have no idea this was shot on the phone,” the filmmaker told IndieWire.

“I’ve seen it 40 feet tall,” Soderbergh said of Unsane. “It looks like velvet.”

He added that he thinks shooting movies on an iPhone or similar device is a “game changer” for filmmaking. He said it was a good experience and he would find it hard to return to the use of usual movie cameras.

Director Steven Soderbergh is shown using an iPhone while shooting on the set of his movie 'Unsane,' which stars actress Claire Foy. (Fingerprint Releasing/Bleecker Street)

Soderbergh said one of the best things about using an iPhone is that it greatly speeds up shooting. The camera can be moved anywhere “in a matter of seconds.” Unsane was completely shot in just two weeks. The director said it was also helpful not to have to make big holes in walls to fit large cameras or attach equipment to the ceiling.

He added that one of the only issues he had was that the iPhone was sometimes affected by strong vibrations.

Joshua Leonard was an actor in the movie. He said being filmed with an iPhone provided fewer distractions during filming. This permitted him to, in his words, “stay in the world of the film and in the world of our characters.”

He added: “There’s nothing more fun as an actor than just being in the thick of the creative process when you’re actually on set. And not having to wait for the machine of filmmaking to catch up with the creative impulse.”

Director Steven Soderbergh and actor Joshua Leonard pose during a photocall to promote the movie Unsane at the 68th Berlinale International Film Festival in Berlin, Germany, Feb. 21, 2018.

​Leonard said it also helped his performance because he is already used to so many people putting phones close to his face to take pictures.

Soderbergh thinks this same idea will help many people develop a deeper connection to the movie. He says this is because people are already completely used to seeing camera phone imagery.

In his words, “I think without even knowing it, there’s an intimacy between the viewer and the screen in this case, because of that familiarity.”

Soderbergh is currently working on another iPhone-filmed movie. That basketball-related film, “High Flying Bird,” is to be released next year.

I’m Caty Weaver. And I’m Bryan Lynn.

Bryan Lynn wrote this story for VOA Learning English, based on reports from the Associated Press, Reuters and other sources. Caty Weaver was the editor.